MACROCYCLIC ARAMIDS (2N-AZA[2N]PARACYCLOPHANE-2N-ONES) - NEW INTERMEDIATES FOR THE SYNTHESIS OF P-ARAMIDS

An easy route to a new class of 2n-aza[2n]paracyclophane-2n-ones, N-su bstituted para-oriented cyclic aromatic amide (cycloaramid) oligomers, is described. The bulky diamine N,N'-di-sec-butyl-p-phenylenediamine is condensed with terephthaloyl chloride at elevated temperature in o- dichlorobenzene to provide a high yield of N,N'-di-sec-butyl-p-phenyle neterephthalamide cyclic oligomers (from dimer to tridecamer). (There is evidence presented for the presence of cyclic unimer (a single repe at unit), an amide analog of [2.2]paracyclophane, in the reaction prod uct!) The cyclization is favored by the cis conformation of the N-subs tituted amide bonds present in the growing chain. Ring-opening polymer ization of these new cycloaramids to high molecular weight linear poly mers can be effected in the melt phase with highly nucleophilic cataly sts such as 1,3-dialkylimidazole-2-thiones, especially when an acid co catalyst is employed. The N-substituted polymers yield crystalline fil ms and fibers with an axial repeat length which can only be explained by an unexpected trans conformation of the amide bonds. The facile syn thesis of other macrocyclic amides by the steric control of macrocycli zation by N-substitution of the amide bond is also described.